No official studies have been conducted on its effects on humans. Though its effects are not well documented, extremely large doses may cause negative effects that are generally not noted in marijuana users, such as increased agitation and vomiting.Professor John W. Huffman who first synthesised many of the cannabinoids used in synthetic cannabis is quoted as saying, "People who use it are idiots". You don't know what it's going to do to you." A three gram package of Spice is said by one study, to have the same health effects on the lungs as a packet of cigarettes, although no conclusive evidence of this exists outside of the study. A user who consumed 3 g of Spice Gold every day for several months showed withdrawal symptoms, similar to those associated with withdrawing from the use of narcotics. Doctors treating the user also noted that his use of the product showed signs associated with addiction. One case has been reported where a user, who had previously suffered from cannabis induced recurrent psychotic episodes, suffered reactivation of their symptoms after using Spice. Psychiatrists treating him have suggested that the lack of an antipsychotic chemical, similar to cannabidiol found in natural cannabis, may make synthetic cannabis more likely to induce psychosis than natural cannabis.